JP2011011661A - Shock absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorbing member capable of attaining buckling deformation in a stable state as well as a large amount of energy absorption upon collision.SOLUTION: The shock absorbing member 2 is a cylindrical member that absorbs shock energy by collapse deformation using a load W working upon collision of an automobile. The shock absorbing member 2 has: a straight cylindrical portion 21 with an inside diameter Dof which is formed to be substantially uniform; a tapered cylindrical portion 22 formed in a tapered shape, an end of which has an outside diameter Ddifferent from an outside diameter Dof the other end; and an intermediate cylindrical portion 23 that is interposed between the other ends of the straight cylindrical portion 21 and the tapered cylindrical portion 22 so that both thereof are coaxially connected to each other. The inside diameter D, the outside diameter Dand the outside diameter Dare formed to have a relationship of D<D<D.

Description

  The present invention relates to an impact absorbing member that absorbs collision energy at the time of automobile collision.

  2. Description of the Related Art Conventionally, a vehicle body frame is known in which a cylindrical shock absorbing member that absorbs collision energy by being crushed and deformed in the axial direction by a load acting during a car collision (for example, Patent Document 1 and Patents). Reference 2).

The impact absorbing member (collision energy absorbing structure) described in Patent Document 1 is a straight cylindrical first cylindrical member formed constant with a small outer diameter and a straight cylindrical member formed constant with a large outer diameter. The cylindrical second cylindrical member and the end of the second cylindrical member are bent in a ring shape on the axial center side, and the ends of the first cylindrical member and the second cylindrical member are joined by arc welding. And a stepped cylindrical body composed of a stepped portion integrated coaxially.
In the collision energy absorbing structure, at the time of collision, the small diameter portion of the stepped portion is curled outward by the collision load, and the large diameter portion is curled inward, so that the collision energy is reduced by continuous plastic deformation. Absorbs.

The cylindrical energy management system described in Patent Document 2 integrally connects a large-diameter first tubular portion, a second tubular portion having a smaller diameter than the first tubular portion, and the first tubular portion and the second tubular portion. And an impact absorbing member (energy management cylinder) continuously formed of heat-treatable steel or the like.
When the bumper system receives an impact in the longitudinal direction, the impact absorbing member is crushed in a nested manner by a certain roll crush that can be predicted by the first cylindrical portion and the second cylindrical portion.

JP 2001-241478 (paragraphs 0007, 0008, FIG. 1 and FIG. 3) Special table 2007-503561 (Claims, FIGS. 1 to 3)

Each of the impact absorbing members described in Patent Literatures 1 and 2 is formed in a shape in which two end portions of straight cylindrical members having different outer diameters are connected in a stepped shape. For this reason, those impact-absorbing members have the effect of being able to stabilize the axial crushing load that is crushed in the axial direction.
However, these shock absorbing members are crushed with a smaller load than when a simple cylinder consisting of one straight cylinder is crushed.
For this reason, it has been desired that both the buckling deformation in a stable state at the time of the collision and the increase in the energy absorption amount by increasing the crushing load at the time of the collision are desired.

  Therefore, the present invention has been developed to solve the above-described problems, and provides an impact absorbing member that buckles and deforms in a stable state in the event of a collision and that has a large amount of energy absorption in the event of a collision. The task is to do.

In order to solve the above-mentioned problem, the invention of the impact absorbing member according to claim 1 is a cylindrical impact absorbing member that absorbs collision energy by being crushed and deformed by a load acting during a collision of an automobile, and has an inner diameter. a straight tubular portion D ₁ is formed in a substantially constant, the tapered cylinder portion formed in a tapered shape in which the outer diameter D ₃ of outer diameter D ₂ and the other end portion of the one end portion are different, the straight tube portion And an intermediate tube portion that is interposed between the other end portion of the tapered tube portion and coaxially connects the straight tube portion and the tapered tube portion, the inner diameter D ₁ , The diameter D ₂ and the outer diameter D ₃ are formed to have a length of D ₃ <D ₁ <D ₂ .

According to such a configuration, the impact absorbing member includes a straight tubular portion of the inner diameter D _1, one end inner diameter D ₁ greater than the outside diameter D _2, the tapered tube of the other end inner diameter D ₁ smaller outer diameter D ₃ By having the portion and the intermediate tube portion, the taper-shaped tube portion is deformed so as to enter inside the straight tube portion during crushing deformation. When the tapered cylindrical portion enters the inner surface of the straight cylindrical portion, the intermediate cylindrical portion is deformed so as to be folded back, and the portion on the small diameter side of the tapered cylindrical portion is crushed while being in contact with the inner surface of the end portion of the straight cylindrical portion. By deforming, the crushing load increases, so that the amount of energy absorption can be increased. In addition, the shock absorbing member concentrates the deformation on the intermediate cylinder portion and generates a large strain, thereby more effectively utilizing the ductility of the material than the conventional structures described in Patent Documents 1 and 2 described above. can do. Furthermore, the impact absorbing member can improve the energy absorbing ability, shorten the crash stroke of the portion that buckles and deforms in the collision, and buckles and deforms in a stable state in the event of the collision. Can be made to

Invention of the shock-absorbing member according to claim 2 is a cylindrical impact absorbing member for absorbing a collision energy by crushing deformed by load acting upon vehicle collision, forming an outer diameter D ₁₀ of substantially constant a straight tubular portion which is a tapered cylindrical portion and the outer diameter D ₃₀ is formed in a tapered shape having different inner diameter D ₂₀ and the other end portion of the one end, the other of the straight tubular portion the tapered tubular portion And an intermediate cylinder portion that is interposed between the end portions and coaxially connected to each other, and the outer diameter D ₁₀ , the inner diameter D ₂₀ , and the outer diameter D ₃₀ are D ₂₀ <D ₁₀ < characterized in that it is formed to a length of D _30.

According to such a configuration, the impact absorbing member includes a straight tubular portion of the inner diameter _{D 10,} one end inner diameter _{D 10} is smaller than outer diameter _{D 20,} the tapered tube of the other end inner diameter _{D 10} is greater than the outside diameter _{D 30} By having the part and the intermediate cylinder part, the taper-shaped cylinder part is deformed so as to be pushed out of the straight cylinder part during crushing deformation. When the tapered tube portion is pushed out to the outer surface of the straight tube portion, the constricted intermediate tube portion is deformed so as to be folded back, and the large diameter side portion of the tapered tube portion is formed on the outer surface of the end portion of the straight tube portion. By crushing and deforming while abutting, the crushing load increases, so that the amount of energy absorption can be increased. For this reason, the invention of claim 2 can obtain the same effect as that of claim 1.

  The invention according to claim 3 is the impact absorbing member according to claim 1 or 2, wherein at least one of the straight tube portion and the tapered tube portion is increased in thickness and quenched. Alternatively, it is characterized in that it is formed with higher strength than the intermediate cylinder part by either changing the material.

  According to this configuration, at least one of the straight tube portion and the tapered tube portion is formed to have a higher strength than the intermediate tube portion, so that when an impact load in the axial direction is applied to the shock absorbing member, The tube portion is more concentrated and buckled.

  According to a fourth aspect of the present invention, there is provided the shock absorbing member according to any one of the first to third aspects, wherein the straight tube portion and the tapered tube portion are substantially polygonal in cross section. The tapered cylindrical portion is formed such that its cross-sectional shape gradually becomes circular as it approaches the intermediate cylindrical portion side.

  According to this configuration, the cross section of the straight tube portion and the tapered tube portion is formed in a substantially polygonal shape, and the cross-sectional shape of the taper tube portion gradually becomes circular toward the intermediate tube portion side. In this way, the connecting side end of the tapered cylindrical portion can easily enter the straight cylindrical portion during buckling deformation. For this reason, when receiving an impact load in the axial direction, the intermediate tube portion is likely to be locally deformed and concentratedly buckled and deformed.

  According to the impact absorbing member of the present invention, the amount of energy absorption at the time of collision can be increased, and the crash stroke of the buckled deformation portion can be shortened, and at the time of the collision, a stable state can be obtained. It can be made to buckle and deform. Moreover, the impact absorbing member can improve the energy absorbing ability by more effectively utilizing the ductility of the material.

It is a perspective view of the body frame which shows an example of the installation state of the impact-absorbing member which concerns on embodiment of this invention. It is a figure which shows the impact-absorbing member which concerns on embodiment of this invention, (a) is a front view, (b) is a top view. (A), (c), (e), (g), (i) is a central sectional view showing a state in which the shock absorbing member is deformed by receiving a load, (b), (d), (f), ( h) and (j) are enlarged views of A part, B part, C part, D part and E part. It is a graph which shows the relationship between the deformation of the impact-absorbing member which concerns on embodiment of this invention, and a load. It is a bar graph which shows the energy absorption amount of the impact-absorbing member which concerns on embodiment of this invention, and the energy absorption amount of an octagonal cross section and Comparative Examples 1 and 2, respectively. It is a graph which shows the relationship between the load in the impact-absorbing member which concerns on embodiment of this invention, an octagonal cross section, and Comparative Examples 1 and 2 and a deformation amount. It is a distribution map of distortion of a plastically deformed shock absorbing member. It is a graph showing the stress-plastic strain characteristic of various materials. It is a bar graph showing the difference between the distortion of the shock absorbing member of the present invention formed of various materials and the distortion of the octagonal cross-section shock absorbing member formed of various materials. It is sectional drawing which shows the 1st modification of the impact-absorbing member which concerns on this invention. It is a bar graph which shows the energy absorption amount of the impact-absorbing member which concerns on embodiment of this invention, and the energy absorption amount of the dodecagonal cylindrical impact-absorbing member and cylindrical impact-absorbing member of a 2nd modification. It is a graph which shows the relationship between the load and deformation | transformation amount in the impact-absorbing member which concerns on embodiment of this invention, the impact absorber of the 12th cylinder shape of a 2nd modification, and a cylindrical impact-absorbing member. It is a figure which shows the 3rd modification of the impact-absorbing member which concerns on this invention, (a) is a top view, (b) is FF sectional drawing of (a), (c) is the H section expansion of (b). FIG. 4D is a partially enlarged view of the connecting portion between the tapered cylindrical portion and the intermediate cylindrical portion. It is a figure which shows the 4th modification of the impact-absorbing member of this invention, (a) is a top view, (b) is GG sectional drawing of (a), (c) is the I section enlarged view of (b). It is. It is a figure which shows the 5th modification of the impact-absorbing member which concerns on this invention, (a) is center sectional drawing, (b) is a center sectional view which shows the state which the impact-absorbing member was crushed and deformed.

  First, an impact absorbing member according to an embodiment of the present invention will be described with reference to the accompanying drawings. Hereinafter, for convenience, the traveling direction of the automobile 1 will be described as “front” and the backward direction as “rear”. Before describing the shock absorbing member 2, the automobile 1 on which the shock absorbing member 2 is mounted will be described.

≪Automobile composition≫
As shown in FIG. 1, a vehicle 1 has a vehicle body frame 10 that forms a skeleton of a vehicle body mounted on a lower portion of the vehicle body. The automobile 1 only needs to have the body frame 10, and the type and type thereof are not particularly limited. Hereinafter, the present invention will be described by taking the case of an FR passenger car as an example.

<Body frame configuration>
The vehicle body frame 10 includes a pair of left and right side frames 11 and 11 extending in the longitudinal direction of the vehicle body, and a plurality of cross members 12 that are installed between the side frames 11 and 11 along the vehicle width direction. It is constructed by welding. The body frame 10 is made of, for example, a high-strength steel material or aluminum alloy having a large plate thickness.

The side frames 11 and 11 are formed by connecting front side frames 13 and 13, floor frames 14 and 14, and rear side frames 15 and 15 from the front side to the rear side. A front bumper beam 16 is installed at the front end portions of the left and right side frames 11 and 11 (front side frames 13 and 13) through shock absorbing members 2 and 2 that absorb shocks at the time of a frontal collision. . Rear bumper beams 17 are installed at rear end portions of the left and right side frames 11 and 11 (rear side frames 15 and 15) with impact absorbing members 2 and 2 for absorbing impacts at the time of rear-end collision, respectively.
For this reason, the side frame 11 has a structure having a crash stroke that is crushed and deformed to absorb the collision energy when the automobile 1 makes a severe frontal collision and rear-end collision by the impact absorbing members 2 and 2.

≪Configuration of shock absorbing member≫
As shown in FIGS. 2A and 2B, the shock absorbing member 2 is a cylindrical member that absorbs collision energy by being crushed and deformed by a load W acting upon a collision of the automobile 1 (see FIG. 1). And has a crash box function. The shock absorbing member 2 is made of, for example, an octagonal cylinder having a uniform thickness, and is made of 780T steel (780 MPa class processing-induced transformation type composite structure high strength steel), 590R steel (590 MPa class precipitation strengthened steel), TWIP (Twining). Induced Plasticity (twinning induced plasticity) steel and other high strength steel. Impact absorbing member 2 includes a straight tubular portion 21 of the inner diameter D ₁ is formed in a substantially constant, tapered to the outer diameter D ₃ of outer diameter D ₂ and the other end portion of the one end portion is formed in a tapered shape which differs A cylindrical portion 22 and an intermediate cylindrical portion 23 connected between the straight cylindrical portion 21 and the tapered cylindrical portion 22 are integrally formed.
The shock absorbing member 2 installed on the front side of the vehicle body is arranged with the tapered cylindrical portion 22 on the front side (side receiving the load W). The shock absorbing member 2 installed on the rear side of the vehicle body has the same shape as that for the front side of the vehicle body, and is disposed with the tapered cylindrical portion 22 on the rear side (side receiving the load W).

The shock absorbing member 2 has an inner diameter D ₁ of the straight tube portion 21, an outer diameter D ₂ of the opening end 22 a of the tapered tube portion 22, and an outer diameter D ₃ of the intermediate tube portion 23.
D ₃ <D ₁ <D ₂
It is formed in the length.

<Configuration of straight tube section>
The straight tube portion 21 is welded so that the opening end 21 a is aligned with the front end portion or the rear end portion of the side frame 11 in the axial center. Straight tubular portion 21 has an inner diameter D ₁ over intermediate tubular portion 23 side is formed to be constant from the opening end 21a.

<Configuration of tapered cylindrical portion>
The tapered end portion 22a of the tapered cylindrical portion 22 is welded to the front bumper beam 16 or the rear bumper beam 17 (see FIG. 1). That is, the tapered cylindrical portion 22 of the shock absorbing member 2 installed on the front side of the vehicle body is arranged with the opening end 22a on the front side so that the load W is applied to the opening end 22a in the case of a frontal collision. The tapered cylindrical portion 22 of the shock absorbing member 2 installed on the rear side of the vehicle body is disposed with the opening end 22a on the rear side so that the load W is applied to the opening end 22a during the rear-end collision. The tapered cylindrical portion 22 is formed with a reduced diameter in a tapered shape from the opening end 21a to the intermediate cylindrical portion 23 side. The tapered cylindrical portion 22 is formed such that the outer diameter D ₃ of the connecting side end portion 22 b is smaller than the outer diameter D ₂ of the opening end 21 a and the inner diameter D ₁ of the straight cylindrical portion 21.

<Configuration of intermediate cylinder>
Intermediate tubular portion 23, by connecting the straight tubular portion 21 and the tapered cylinder portion 22, the straight tube portion 21 side is formed on the inner diameter D _1, tapered cylinder portion 22 side is formed on the outer diameter D ₃ ing. For this reason, the intermediate | middle cylinder part 23 is formed in the state expanded from the taper-shaped cylinder part 22 side to the straight cylinder part 21 side.

≪Operation of shock absorbing member≫
Next, the operation of the shock absorbing member 2 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 9 by taking as an example a case where the automobile 1 has a severe frontal collision (frontal collision) with another vehicle. .
The impact absorbing member 2 disposed on the front side of the vehicle and the impact absorbing member 2 disposed on the rear side of the vehicle have the same effects when receiving the load W. Hereinafter, only the shock absorbing member 2 disposed on the front side of the vehicle will be described, and description of the shock absorbing member 2 disposed on the rear side of the vehicle will be omitted.

<About deformation of shock absorbing member>
First, the deformation of the shock absorbing member 2 at the time of collision will be described in time series with reference to FIGS.
As shown in FIG. 1, when the automobile 1 is traveling, for example, when a severe frontal collision occurs with another vehicle, a front bumper (not shown) and a front bumper beam 16 installed at the front of the automobile 1 are The front end portion (opening end 22 a) of the tapered cylindrical portion 22 of the shock absorbing member 2, 2 is pressed through the front bumper beam 16 by being pressed rearward by another vehicle.

  As shown in FIG. 3A, the load (axial crushing load) W applied to the shock absorbing member 2 presses the open end 22 a of the tapered cylindrical portion 22. Then, the tapered cylindrical portion 22 presses the intermediate cylindrical portion 23 to intensively buckle and deform the intermediate cylindrical portion 23 as shown in FIGS. 3 (c), (e), (g), and (i). Let

That is, the outer diameter D ₃ of the connection side end 22 b on the intermediate cylinder portion 23 side of the tapered cylinder portion 22 is formed to be smaller than the inner diameter D ₁ of the straight cylinder portion 21. For this reason, the shock absorbing member 2 is deformed while the connecting side end portion 22b of the tapered cylindrical portion 22 moves so as to enter and enter the straight cylindrical portion 21, so that the intermediate cylindrical portion 23 is stably folded back. In this state, the outer peripheral surface near the connection side end 22b of the tapered cylindrical portion 22 presses the inner surface of the load load side end 21b of the straight cylindrical portion 21 via the intermediate cylindrical portion 23. By deforming, the crushing load increases. For this reason, the amount of energy absorption can be increased.
3 (g), (h), (i), and (j), the shock absorbing member 2 is configured such that the connecting side end portion 22b of the tapered cylindrical portion 22 has a load applied to the straight cylindrical portion 21. When the side end 21b is pulled into the straight tube portion 21 while being pulled into the straight tube portion 21, the load end side portion 21b of the intermediate tube portion 23 and the straight tube portion 21 is pulled into the straight tube portion 21 and stopped. To do. The collision load (axial crushing load) W is absorbed by buckling deformation of the load-load side end portion 21b of the intermediate tube portion 23 and the straight tube portion 21.

  Accordingly, the left and right side frames 11 shown in FIG. 1 concentrate energy on the intermediate cylinder portion 23 of the shock absorbing members 2 and 2 and generate a large distortion when the automobile 1 is in a frontal collision, thereby generating energy. The absorption capacity can be improved, and the crash stroke of the portion that buckles and deforms in the event of a collision can be shortened.

  Since the shock absorbing members 2 and 2 can install a crushable zone that is crushed in the event of a collision at the front end portion of the side frames 11 and 11, the collision energy at the time of the collision at the front end portion of the body frame 10. Can be absorbed and the impact can be received locally. For this reason, the impact absorbing members 2 and 2 can suppress the impact from being transmitted to the rear of the vehicle body from the impact absorbing members 2 and 2. Further, the shock absorbing members 2 and 2 relieve the impact applied to the members located behind the vehicle from the intermediate cylinder 23, and the members located behind the shock absorbing members 2 and 2 are deformed by the load W at the time of collision. It can suppress destruction.

  Even when another vehicle collides with the automobile 1 shown in FIG. 1, the impact absorbing members 2 and 2 arranged at the rear part of the vehicle body absorb the rear-end collision load as in the case of a frontal collision.

<Relationship between deformation and load>
Next, the relationship between the amount of deformation and the load when the shock absorbing member 2 is deformed will be described with reference to FIGS. 3 and 4. FIG. 4 is a graph showing the relationship between the amount of deformation and the load of the shock absorbing member according to the embodiment of the present invention.

  As shown in FIG. 4, when the automobile 1 collides head-on and the shock absorbing member 2 starts to deform due to the axial load W, a large load W is applied to the shock absorbing member 2 as shown in part a. . When the shock absorbing member 2 starts to deform, the connection side end portion 22b of the tapered cylindrical portion 22 enters the straight cylindrical portion 21 while pressing and buckling the intermediate cylindrical portion 23 with a load W weaker than the a portion ( (States (c) and (d) in FIG. 3).

  When the connection side end portion 22 b of the tapered cylindrical portion 22 further enters the straight cylindrical portion 21, it contacts the inner wall of the straight cylindrical portion 21. Then, the load W starts to rise from the portion b (states (e) and (f) in FIG. 3).

Further, when the load-load side end portion 21b of the straight tube portion 21 is buckled and pulled into the straight tube portion 21, the amount of deformation increases from the c portion to the d portion due to the wedge effect by the tapered tube portion 22. At the same time, the load W increases (states (g), (h), (i), and (j) in FIG. 3). That is, the energy absorption efficiency of the shock absorbing member 2 is increased.
Then, when the amount of deformation of the shock absorbing member 2 increases to the e portion, buckling deformation of the straight tube portion 21 starts and the load increases.

<About energy absorption>
Next, the energy absorption amount of the shock absorbing member 2 will be described in comparison with a conventional shock absorbing member with reference to FIGS. FIG. 5 is a bar graph showing the energy absorption amount of the shock absorbing member of the present invention, and the energy absorption amounts of the octagonal cross section and Comparative Examples 1 and 2, respectively. FIG. 6 is a graph showing the relationship between the load W and the amount of deformation in the impact absorbing member, octagonal cross section, and comparative examples 1 and 2 of the present invention.

  As shown in FIG. 5, the shock absorbing member 2 of the present invention includes a straight shock absorbing member 100 having an octagonal cross section, a comparative example 1 of an octagonal tubular body 200 having a stepped intermediate portion 201, and an inclined intermediate tubular portion. Compared with the comparative example 2 of the octagonal cylinder 300 having 301, an experimental result that the amount of energy absorption is large was obtained. As shown in FIG. 5, the energy absorption amount of the shock absorbing member 2 of the present invention is larger by L (1.6 kJ) than the shock absorbing member 100 having an octagonal cross section of the same weight.

  Further, as shown in FIG. 6, in the shock absorbing member 2 of the present invention, the intermediate tube portion 23 side of the tapered tube portion 22 described above enters the straight tube portion 21 and the load on the intermediate tube portion 23 and the straight tube portion 21. The load W with respect to the deformation amount when the load side end portion 21b is buckled and deformed is larger as a whole than the impact absorbing member 100 having the octagonal cross section and the comparative examples 1 and 2.

<Distortion of plastically deformed impact absorbing member>
Next, the distortion of the impact absorbing member 2 plastically deformed will be described with reference to FIG. FIG. 7 is a strain distribution diagram of the impact-absorbing member 2 plastically deformed.
As shown in FIG. 7, the shock absorbing member 2 has a straight cylindrical portion when the automobile 1 (see FIG. 1) collides front and the connection side end portion 22 b of the tapered cylindrical portion 22 bites into the straight cylindrical portion 21. The load-load side end 21b 21 receives a tensile force in the circumferential direction, and a uniform distortion occurs. Then, the distortion of the shock absorbing member 2 having an octagonal cross section in the cross section is concentrated on the corner portion 2a of the concentric intermediate tube portion 23 and becomes high. Thus, since the shock absorbing member 2 is buckled and deformed with a large strain concentrated on the intermediate tube portion 23, most of the straight tube portion 21 is not distorted and the deformation amount is small. Is possible.

<Difference in strain due to material properties>
Next, with reference to FIG.8 and FIG.9, the difference in the distortion by the material characteristic used for the impact-absorbing member 2 is demonstrated. FIG. 8 is a graph showing stress-plastic strain characteristics of various materials. FIG. 9 is a bar graph showing the difference between the absorbed energy amount of the shock absorbing member of the present invention formed of various materials and the absorbed energy amount of the octagonal cross section formed of various materials.

Plasticity against stress when the shock absorbing member 2 of the present invention and the shock absorbing member 100 having an octagonal cross section (see FIG. 5) are formed of 780T steel (f), 590R steel (g), and TWIP steel (h), respectively. The distortion is as shown in FIG. FIG. 8 shows that among these materials, the stress when the shock absorbing member 2 is formed of TWIP steel (h) is the highest, and the stress when formed of 780T steel (f) is the lowest. It was.
Thus, the impact absorbing member 2 can be further crushed with a large load W by being formed of TWIP steel (h) having high strength and high ductility.

Further, as shown in FIG. 9, the shock absorbing member 2 of the present invention and the shock absorbing member 100 having an octagonal cross section (see FIG. 5) are made of 780T steel (f), 590R steel (g), and TWIP steel (h). When the energy absorption amount (kJ) in the case of each of the materials is compared, the energy absorption amount of the shock absorbing member 2 of the present invention is larger in all materials than the shock absorbing member 100 having an octagonal cross section (see FIG. 5). Results were obtained.
In particular, when the entire shock absorbing member 2 is formed of TWIP steel (h), the energy absorption amount is large, and the energy absorption ability is significantly improved. Since the shock absorbing member 2 generates high strain in the tapered cylindrical portion 22 having the constricted shape as described above, a material having high strength and high ductility in a high strain region such as TWIP steel (h) is used. As a result, the energy absorption effect can be further improved.

[Modification]
The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the technical idea. The present invention extends to these modifications and changes. Of course.

≪First modification≫
FIG. 10 is a cross-sectional view showing a first modification of the shock absorbing member according to the present invention.
In the embodiment, as shown in FIG. 2, as an example of the impact absorbing member 2, the opening end 22 a side of the tapered cylindrical portion 22 that expands in a tapered shape and has the largest outer diameter D ₂ in the impact absorbing member 2 is used. Although what was arrange | positioned on the side to which the load W is loaded was demonstrated, it is not limited to this. For example, as in the impact absorbing member 3 shown in FIG. 10, any cylindrical body having a straight cylindrical portion 31, a tapered cylindrical portion 32, and an intermediate cylindrical portion 33 may be used.

Impact-absorbing member 3 has a straight tubular portion 31 having an outer diameter D ₁₀ of which is formed in a substantially constant, connecting-side end portion 32 b (the other end to the inner diameter D ₂₀ of the opening end 32a side of the load W is loaded (one end) a tapered tubular portion 32 and the outer diameter D ₃₀ is tapered to different parts), between the connecting-side end portion 32b of the straight tubular portion 31 and the tapered cylinder portion 32 (the other end) And an intermediate cylinder portion 33 that is interposed and coaxially connected to each other.
The outer diameter D ₁₀ , inner diameter D ₂₀ , and outer diameter D ₃₀ are:
D ₂₀ <D ₁₀ <D ₃₀
You may form so that it may become.
That is, the tapered cylinder portion 32, thin side load W is applied is reduced in diameter, the connecting-side end portion 32b of the intermediate cylinder portion 33 side is formed to be the maximum outer diameter D _30.

By forming the shock absorbing member 3 in this manner, when an excessive load W is applied to the opening end 32a of the tapered cylindrical portion 32, the connecting side end portion 32b extends from the outer periphery of the intermediate cylindrical portion 33 to the straight cylinder. While being pushed out to the outer peripheral side of the part 31 and deforming so that the intermediate cylinder part 33 is folded back,
The inner surface of the tapered cylindrical portion 32 near the connection side end portion 32b is buckled and deformed while pressing the outer surface of the load loading side end portion 31b of the straight cylindrical portion 31 via the intermediate cylindrical portion 33, so that the crushing load is reduced. To rise. For this reason, also in the case of a 1st modification, there exists an effect that the amount of energy absorption can be increased similarly to the said embodiment.

≪Second modification≫
FIG. 11 is a bar graph showing the energy absorption amount of the shock absorbing member according to the embodiment of the present invention and the energy absorption amount of the twelve-cylindrical shock absorbing member and the cylindrical shock absorbing member of the second modified example. is there. FIG. 12 is a graph showing the relationship between the load and the amount of deformation in the shock absorbing member of the present invention, the twelve-cornered shock absorbing member of the second modified example, and the cylindrical shock absorbing member.

  In the embodiment and the first modified example, the octagonal cylindrical shock absorbing members 2 and 3 have been described. However, the shock absorbing members 2 and 3 are, as shown in FIG. Alternatively, it may be a cylindrical shock absorbing member 5. In other words, the impact absorbing members 4 and 5 may be cylindrical as long as the shape of the cross section in the direction perpendicular to the axis is cylindrical.

  In this case, an experimental result was obtained that the impact absorption member 4 having a dodecagonal tube shape shown in FIG. 11 has a larger energy absorption amount than the impact absorption member 2 of the above embodiment. Moreover, the cylindrical-shaped impact-absorbing member 5 obtained the energy absorption amount substantially equivalent to the impact-absorbing member 2 of the said embodiment. The twelve-corner-shaped shock absorbing member 4 has a square twill portion 4a in the constricted intermediate tube portion 43, so that the intermediate tube portion 43 has a large distortion, and a large number of distortions occur and the region where the distortion occurs increases. Therefore, it is considered that the amount of energy absorption is increasing.

  As shown in FIG. 12, the impact absorbing member 4 and the impact absorbing member 5 having a cylindrical shape have a large load W to be crushed and deformed in substantially the same manner as the impact absorbing member 2 of the present invention described above. The experimental results were obtained.

<< Third Modification >>
13A and 13B are views showing a third modification of the shock absorbing member according to the present invention, in which FIG. 13A is a plan view, FIG. 13B is a sectional view taken along line FF in FIG. 13A, and FIG. (D) is the elements on larger scale of the connection part of a taper-shaped cylinder part and an intermediate | middle cylinder part.
As shown in FIGS. 13A to 13D, the shock absorbing member 6 has a radius R2 of the corner portion 6a of the tapered tubular portion 62 larger than a radius R1 of the corner portion 6a of the straight tubular portion 61, and You may form in circular arc shape. As described above, the shock absorbing member 2 increases the radius R2 of the corner portion 6a of the tapered cylindrical portion 62, thereby increasing the corners of the corner portion 6a of the straight cylindrical portion 61 and the connecting side end portion 62b of the tapered cylindrical portion 62. offset S between Ayabe 6a (the difference between the inner diameter _{D 1} and an outer diameter _{D 3)} increases. By forming the shock absorbing member in this manner, the corner portion 6a of the straight tube portion 61 and the corner portion 6a of the connecting side end portion 62b of the tapered tube portion 62 are less likely to interfere with each other during crushing deformation. For this reason, the tapered cylindrical portion 62 easily enters the straight cylindrical portion 61 when being crushed and is stably crushed.

<< Fourth Modification >>
14A and 14B are views showing a fourth modification of the shock absorbing member according to the present invention, in which FIG. 14A is a plan view, FIG. 14B is a sectional view taken along line GG in FIG. 14A, and FIG. FIG.
As shown in FIGS. 14A to 14C, as the shock absorbing member 7 approaches the tapered cylindrical portion 72 toward the intermediate cylindrical portion 73, the cross-sectional shape thereof is a substantially octagonal shape (substantially). You may form so that it may become circular gradually from a polygonal shape. That is, the connection side end portion 72b of the tapered cylindrical portion 72 is formed such that the corner portion 7a is eliminated and the round R4 is circular. For this reason, the radius R4 is larger than the radius R3 of the corner portion 7a of the straight tube portion 71.
Even if it does in this way, the effect similar to the impact-absorbing member 6 of the said 3rd modification can be acquired.

<< Fifth Modification >>
15A and 15B are views showing a fifth modification of the impact absorbing member according to the present invention, in which FIG. 15A is a central sectional view, and FIG. 15B is a central sectional view showing a state where the impact absorbing member is crushed and deformed.
As shown in FIGS. 15A and 15B, the shock absorbing member 8 has a thickness t1, t2 of at least one of the straight cylindrical portion 81 and the tapered cylindrical portion 82 that is greater than the thickness t3 of the intermediate cylindrical portion 73. Also, the strength of the straight tube portion 81 or the tapered tube portion 82 can be made higher than that of the intermediate tube portion 73.

In this way, when the crushing load W is applied to the impact absorbing member 8, the strain can be concentrated on the constricted intermediate tube portion 73. That is, by reinforcing the tapered cylindrical portion 82 and the straight cylindrical portion 81 and suppressing deformation at the time of collision, as shown in FIG. Since a tensile load acts on the tapered cylindrical portion 82 and is dispersed in the intermediate cylindrical portion 83, the strain is concentrated on the intermediate cylindrical portion 83 and further generated.
As a result, when the crushing load W is applied to the impact absorbing member 8, it is possible to prevent the tapered cylindrical portion 82 and the straight cylindrical portion 81 from being buckled easily.

  The tapered cylindrical portion 82 and the straight cylindrical portion 81 may be changed in strength by quenching instead of changing the plate thicknesses t1, t2, and t3, or may be changed to materials having different strengths. Accordingly, the intermediate cylinder portion 83 may be formed to have a higher strength. Also in this case, the same effect as the fifth modified example can be obtained.

1 Automobile 2, 3, 4, 5, 6, 7, 8 Strike absorbing member 21, 31, 61, 71, 81 Straight tube portion 22, 32, 62, 72, 82 Tapered tube portion 23, 33, 43, 63 , 73 and 83 intermediate tubular portion D _{1, D 20} inner diameter _{D 2, D 3, D 10} , D 30 outer diameter t1, t2, t3 thickness W load

Claims (4)

A cylindrical shock absorbing member that absorbs collision energy by being crushed and deformed by a load acting during a car collision,
A straight tubular portion inner diameter D ₁ is formed in a substantially constant,
A tapered cylindrical portion and the outer diameter D ₃ of outer diameter D ₂ and the other end portion of the one end portion is formed in a tapered shape which differs,
An intermediate tube portion that is interposed between the straight tube portion and the other end portion of the tapered tube portion and coaxially connects the straight tube portion and the tapered tube portion;
The inner diameter D ₁ , the outer diameter D ₂ , and the outer diameter D ₃ are
D ₃ <D ₁ <D ₂
An impact-absorbing member characterized by being formed to a length of A cylindrical shock absorbing member that absorbs collision energy by being crushed and deformed by a load acting during a car collision,
A straight tubular portion having an outer diameter D ₁₀ of which is formed in a substantially constant,
A tapered cylindrical portion and the outer diameter D ₃₀ of the inner diameter D ₂₀ and the other end portion of the one end portion is formed in a tapered shape which differs,
An intermediate tube portion interposed between the straight tube portion and the other end portion of the tapered tube portion and connected on the same axis; and
The outer diameter D ₁₀ , the inner diameter D ₂₀ , and the outer diameter D ₃₀ are
D ₂₀ <D ₁₀ <D ₃₀
An impact-absorbing member characterized by being formed to a length of At least one of the straight tube portion and the tapered tube portion is
The impact absorbing member according to claim 1 or 2, wherein the impact absorbing member is formed to have a higher strength than the intermediate tube portion by increasing the plate thickness, quenching, or changing the material. The straight tube portion and the tapered tube portion are formed in a substantially polygonal cross section,
4. The taper-shaped cylindrical portion is formed so that its cross-sectional shape gradually becomes circular as it approaches toward the intermediate cylindrical portion. The impact absorbing member according to claim 1.

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